1. Field of the Invention
The present invention relates to a progressive gaming system capable of giving a prize, such as pay-out of coins, tokens and the like, for a winning combination formed in a main game played in each of gaming machines associated with each other, and capable of giving a bonus prize, value of which can be progressively increased.
2. Description of the Related Art
A progressive gaming system is known as a system in which a certain rate of medals, coins or tokens, bet in a plurality of gaming machines are collectively accumulated as a progressive bonus, and when a specific combination is formed in any gaming machine, the progressive bonus is paid out to a player of that gaming machine to thereby give the feeling of a so-called jackpot to the player (for example, refer to U.S. Pat. No. 4,837,728).
In this type of the gaming system, the condition for getting the progressive bonus is tended to strictly set in consideration of the character of the progressive bonus. As an example in a poker game machine, only a combination having an extremely low probability such as a so-called royal straight flush is set as a combination for which the progressive bonus is paid out.
However, the setting of the above mentioned strict condition reduces a frequency at which the progressive bonus is paid out, so that the interest of the player is lost. In particular, an interval between each of the pay-out of the progressive bonuses is extremely long in a small system in which only several gaming machines are connected to a single progressive unit, and the value of the progressive bonus accumulated between the intervals is not largely increased. Therefore, the player tends to play the game without substantially giving attention to the existence of the progressive unit.
A system described below is proposed in Japanese Patent Application Laying Open (KOKAI) No.7-148307 which is equivalent to U.S. Pat. No. 5,645,486. That is, if a predetermined combination associated with a bonus chance is formed in the main game played in the gaming machine, the progressive unit performs a lottery as to whether or not the progressive bonus should be paid out in accordance with a probability adjusted in consideration of the amount of the bets by the player at that time. Then, the progressive bonus is paid out in a case of the win in the lottery. According to this system, a chance of getting the progressive bonus is increased to thereby enable the player to be conscious of the existence of the progressive bonus. However, in the above mentioned system, only whether or not the progressive bonus should be paid out is determined by the lottery, and only the result of the lottery is displayed to the player. Thus, this system is not sufficient to impress the existence of the progressive unit on the player. Moreover, there may be a case that even if the progressive bonus is paid out, the player can not understand the reason of the pay-out. For this reason, this system is not sufficient to make the interest of the player to the gaming system with the progressive unit stronger than the interest to the gaming machine without the progressive unit.
In the progressive gaming system, it can be possible that a plurality types of the main games are selectively performed in each of the gaming machines liked to the common progressive unit. However, in this case, the probabilities at which the winning combinations are formed are changed on the basis of the game types. Therefore, it is difficult to uniformly generate the chances of getting the progressive bonuses. Unless the progressive bonuses are appropriately distributed by considering that point, the interest of the player to the progressive gaming system is reduced on the contrary.